We had a chance to install/tune 2 different GT-R's with the billet aluminum Forge actuator kits. Many of you have asked which spring you should run, and we now have some good data to share with everyone.

If you are running an external boost controller, such as the HKS EVC 6, here are the SUSTAINED "BASE" boost pressures you will see with the boost controller turn off. We run 1-2mm of preload. The biggest benefit to running an external boost controller, is the ability to switch to different boost levels on the fly, without having to stop and reflash the ECU. We create one calibration that covers all boost levels for a given type of fuel.

The Forge actuator allows for higher boost levels, less boost tamper, and more power, but we are still reaching the limits of the stock turbocharger and injectors. We are just touching 100% duty cycle at about 18psi sustained boost, which delivers about 525whp on our dyno (baseline stock is 390-400whp).

Upgrading to larger injectors is very straightforward, and we have calibrations for different sized injectors. But for those that want significantly more power, a turbo upgrade is the next logical step.

The OEM turbos are rated at about 30 lb/min worth of air each, so in THEORY, we should see 600bhp out of them. We are seeing about 525whp wich puts us slightly beyond their theoretical max airflow. Remember, the presssure or PSI is not the deciding factor in power production....rather...it's the volume of air usually measured in lb/min that determines airflow power potential. The turbo upgrades on the market, from what we have been told, flow roughly 40 lb/min worth of airflow, which would give a theoretical maximum power of 800bhp.

We also noted that air inlet temps reached 120F after 4-5 consecutive runs, pointing towards the definate need for high capacity intercoolers.

One final point, is that many dynos read very differently, so please use my numbers in the context in which they are stated. I don't want to get into a dyno numbers debate in this thread.

We had a chance to install/tune 2 different GT-R's with the billet aluminum Forge actuator kits. Many of you have asked which spring you should run, and we now have some good data to share with everyone.

If you are running an external boost controller, such as the HKS EVC 6, here are the SUSTAINED "BASE" boost pressures you will see with the boost controller turn off. We run 1-2mm of preload. The biggest benefit to running an external boost controller, is the ability to switch to different boost levels on the fly, without having to stop and reflash the ECU. We create one calibration that covers all boost levels for a given type of fuel.

The Forge actuator allows for higher boost levels, less boost tamper, and more power, but we are still reaching the limits of the stock turbocharger and injectors. We are just touching 100% duty cycle at about 18psi sustained boost, which delivers about 525whp on our dyno (baseline stock is 390-400whp).

Upgrading to larger injectors is very straightforward, and we have calibrations for different sized injectors. But for those that want significantly more power, a turbo upgrade is the next logical step.

The OEM turbos are rated at about 30 lb/min worth of air each, so in THEORY, we should see 600bhp out of them. We are seeing about 525whp wich puts us slightly beyond their theoretical max airflow. Remember, the presssure or PSI is not the deciding factor in power production....rather...it's the volume of air usually measured in lb/min that determines airflow power potential. The turbo upgrades on the market, from what we have been told, flow roughly 40 lb/min worth of airflow, which would give a theoretical maximum power of 800bhp.

We also noted that air inlet temps reached 120F after 4-5 consecutive runs, pointing towards the definate need for high capacity intercoolers.

One final point, is that many dynos read very differently, so please use my numbers in the context in which they are stated. I don't want to get into a dyno numbers debate in this thread.

Hey Sharif

On this subject did you talk to Eric about what we talked about the other day?

Sharif, you're the man! When other people that know don't bother to post important info to help the community, you go that EXTRA bit!! Thanks a LOT!

Sharif, have you found the limit to the OEM fuel pump?

Sharif@Forged, on Apr 25 2009, 02:36 PM, said:

We had a chance to install/tune 2 different GT-R's with the billet aluminum Forge actuator kits. Many of you have asked which spring you should run, and we now have some good data to share with everyone.

If you are running an external boost controller, such as the HKS EVC 6, here are the SUSTAINED "BASE" boost pressures you will see with the boost controller turn off. We run 1-2mm of preload. The biggest benefit to running an external boost controller, is the ability to switch to different boost levels on the fly, without having to stop and reflash the ECU. We create one calibration that covers all boost levels for a given type of fuel.

The Forge actuator allows for higher boost levels, less boost tamper, and more power, but we are still reaching the limits of the stock turbocharger and injectors. We are just touching 100% duty cycle at about 18psi sustained boost, which delivers about 525whp on our dyno (baseline stock is 390-400whp).

Upgrading to larger injectors is very straightforward, and we have calibrations for different sized injectors. But for those that want significantly more power, a turbo upgrade is the next logical step.

The OEM turbos are rated at about 30 lb/min worth of air each, so in THEORY, we should see 600bhp out of them. We are seeing about 525whp wich puts us slightly beyond their theoretical max airflow. Remember, the presssure or PSI is not the deciding factor in power production....rather...it's the volume of air usually measured in lb/min that determines airflow power potential. The turbo upgrades on the market, from what we have been told, flow roughly 40 lb/min worth of airflow, which would give a theoretical maximum power of 800bhp.

We also noted that air inlet temps reached 120F after 4-5 consecutive runs, pointing towards the definate need for high capacity intercoolers.

One final point, is that many dynos read very differently, so please use my numbers in the context in which they are stated. I don't want to get into a dyno numbers debate in this thread.

We have them in stock. We have tested the 710cc, and 800cc. The GT-R injectors are undergoeing some additional balancing testing before they leave, so expect the price to be about $799 for the set....same price as a large set of 350Z injectors, so no GT-R taxes there.

elpasogtr, on Apr 26 2009, 01:51 AM, said:

what is the installation like on these???? Is it extreamly difficult?

It's a very involved install, and requires the removal of just about everything to make space. Not something for the DIY's, but definately something that a well trained technician can tackle over the course of a couple of days or so.

celsius, on Apr 26 2009, 02:30 AM, said:

Sharif, you're the man! When other people that know don't bother to post important info to help the community, you go that EXTRA bit!! Thanks a LOT!

Sharif, have you found the limit to the OEM fuel pump?

Thank you...that means a lot. No fuel pressure issues yet. Based on the turbo upgrade car I just tuned (but can't post about yet), I would say that the OEM fuel pump will support the current turbo upgrade and injectors choices on the market.

I'm a little confused by the stock actuators. The tuners such as Switzer are running stock actuators and are hold more boost to redline and making more power. Why is it that the stock turbo's/actuator combo can't do this. I feel stupid even asking this question but there is some disparity in the logic behind this.

I'm a little confused by the stock actuators. The tuners such as Switzer are running stock actuators and are hold more boost to redline and making more power. Why is it that the stock turbo's/actuator combo can't do this. I feel stupid even asking this question but there is some disparity in the logic behind this.

Im not by any means a good source of info but what I know or think i understand is
switzer does not run stock actuators...
What boost are they running, is it peak psi, is it steady, does it hold. ect..
They use a EVC 6 boost controler in all of their packages
There is no disparity among the best tuners Sharif being one of them

GTR #1. Bucket of bolts, traded for 2012 black edition.

GTR #2 ---2009 RED - Titeck spoiler and other carbon fiber parts.This car is a tank. Has never had a problem in 4 years.

I'm a little confused by the stock actuators. The tuners such as Switzer are running stock actuators and are hold more boost to redline and making more power. Why is it that the stock turbo's/actuator combo can't do this. I feel stupid even asking this question but there is some disparity in the logic behind this.

Boost pressure is falling off, partly due to the WG, but mostly becuase the turbocharger is well out of it's efficiency range. Larger turbos, like the ones that Switzer are using will allow for far more airflow (power) at the same boost pressure.

I somewhat alluded to it in my opening post, but airflow (lb/min) is the key to making power..not pressure. I can have two turbochargers both making 18psi, but each flowing vastly different masses of air. This is why a turbo upgrade at 18psi can make 600whp, while a stock turbo at 18psi might make just 525whp.

Our dyno also reads very low, compared to the DynoJets that many tuners are using. We are making 125whp over stock whp, with the stock turbos...that is the key takeaway. With a turbo upgrade and larger injectors, we see 225whp over stock.

Oftentimes, terms are thrown around very loosely by all of us...myself included. When someone says they are making 20lbs of boost, where did this number come from? Is it the number they see on their gajge? At what RPM? Is this a peak or sustained number. How does the curve look. What if I am making 20psi at peak, and then it tapers to 16psi. So am I running 20psi, or 16psi...LOL..do you see how this can get confusing.